#!perl -w
use strict;
use Tk;

my $mw=MainWindow->new(-title=>'Time');
my $cv=$mw->Canvas(-height => 25, -width => 150)->pack;
my $i=0; 
my $l=undef;

sub t 
{
    $cv->delete( $l ) if defined $l; 
    $l = $cv->create( 'text', 75, 15, -text => scalar( localtime( time() ) ) );
}

$cv->repeat( 250, \&t, $cv ); 

MainLoop